Process of making heat transfer units



033331947. H; F. BRINEN 2,433,731

PROCESS OF MAKING HEAT TRANSFER UNITS Filed Aug. 20, 1945 2 Sheets-Sheet1 1947. H. F. BRINEN YROCESS 01f MAKING HEAT TRANSFER UNITS Filed Aug.20, 1945 2 Sheets-Shoot 2 gnaz I g. I

l 3.. a 2 z Patented Dec. 30, 1947 UNITED STATES PATENT OFFICE I2,433,731 rnocnss or MAKING HEAT TRANSFER UNITS Howard F. Brinen,Racine, Wis., assignor to Young Radiator Company, Racine, Wis., acorporation of Wisconsin Application August 20, 1945, Serial No. 611,518

engines used with aircraft operating in rarified atmosphere. However, adevice of the character herein presented could be used for conditioningother fluids and under other circumstances. Therefore, the applicationof this invention to this particular type of aircraft device is notintended to exclude its use with other types of heat exchange apparatus.

A heat exchange device of the type under consideration involves abattery of tubes through which one current of air is required to flowand around which in a cross-wise direction another current of air iscaused to flow. The major concern in all such tubular structures is tosecure the maximum transfer or exchange of heat between the two aircurrents passing respectively through and around the tubes. A minorconcern is to provide such a union and support of the tubes and thesupporting plates as will insure a high degree of rigidity for the tubesand so firm a bonding thereof with the supporting plates that there canbe no vibration of the tubes and no fluid leakage between the two setsof passages.

2 Claims. (Cl. 29-1573) The efficiency of heat transfer or exchange in aunit of this kind is materially affected by the shape of the tubes. Flattubes are more efllcient by far than circular tubes. However, the tubeshave to be of a seamless type since it is not possible otherwise toprovide an absolutely leakproof unit. Moreover, when these units areused with aircraft it is most desirable to reduce the weight as greatlyas possible. Accordingly, structures of this kind preferably must bemade of aluminum.

The expense of forming seamless flat tubes is materially greater thanforming seamless round tubes. The former have to be bench-drawn whereasthe latter, at least with aluminum, can be formed by what is commonlyknown in the industry as the "impact extrusion or Hooker process. Thisprocess reduces seamless tube manufacturing cost about one-third underany other method. However, the latter process is limited to theformation of round tubes.

Although flat or elliptical tubes are more eflicient from the standpointof heat exchange or transfer, former methods of securing flat tubes tothe header and intermediate reinforcing plates has been difiicult andexpensive from a manufacturing standpoint.

The main objects of this invention, therefore, are to provide animproved method of constructing a supercharger intercooler oraftercooler wherein the tubes are of a flat construction between thesupporting plates; to provide an improved method of forming a flat tubewith circular ends and intermediate circular portions; to provide animproved method of fabricating the tubes thus formed with reinforcingand header plates; and to provide a supercharger intercooler oraftercooler of this type which is simple and inexpensive to manufacture,which possesses maximum structural rigidity, and which is highlyefficient in operation.

In the particular embodiment shown in the accompanying drawings:

Fig. 1 is a perspective view of a completely assembled superchargerintercooler or aftercooler;

Fig. 2 is an enlarged side view of one of the tubes which has beenflattened for use in connection with a supporting plate assembly inaccordance with this invention;

Fig. 3 is a cross-sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged cross-sectional view of the tube showing it in theposition, with regard to an aperture or perforation in the reinforcingplate, wherein it is inserted through said plate;

Fig. 5 is a similar view showing the tube turned 90 which is permissiblewhen the circular part thereof is in registration with the reinforcingplate and whereupon the tube becomes locked in place;

Fig. 6 is an enlarged fragmentary elevation of one corner of one of theintermediate reinforcing plates showing the form and arrangement ofapertures, or perforations therein;

Fig. 7 is a perspective of the hand tool used to turn the tubes afterthey have been inserted through the reinforcing intermediate plate andone header plate;

Fig. 8 is a fragmentary part of one header plate showing the scoringswherewith the pointer on the hand tool registers for indicating theangle of the long dimension of the corresponding tube;

Fig. 9 is a perspective view of the fabrication of all the plates,except one header plate, which go to make up the assembly wherein thetubes are supported;

Fig. 10 is a similar view with all of the tubes in place and showing amandrel base member whereon is placed the other header plate preparatoryto its being placed upon the exposed ends of the tubes; and

Figs. 11, 12, and 13 are enlarged fragmentary v the tubes is exposed inheat exchange relationship with the passage of another fiuidtransversely around and across the battery of tubes.

The fabrication or assembly I2 as herein shown comprises header platesI4 and I and one or more intermediate reinforcing plates I6, all ofwhich are secured together in their desired spaced relationship by aseries of oppositely arranged transverse interconnecting plates IT. Theheader plates I4 and I5 and the intermediate reinforcing plates I6 areapertured in order to receive the tubes I3. The apertures I8 in theheader plates I4 and I5 are circular so as to receive the circular endsof the tubes I3. The apertures II! in the intermediate plates I6 areconstituted of intersecting circular and elliptical punchings ordrillings, the former conforming with the circular portions of the tubesI3, and the latter conforming with the fiat portion of the tubes I3, aswill more clearly hereinafter appear.

The interconnecting plates II are flanged along their lateral edgeswhereby they may be suitably secured to the opposed faces of the platesI4, I5, and I6. This attachment of the plates may be by means of anysuitable form of welding, rivets, or bolts and nuts.

The tubes I3 are first formed by the impact extrusion or Hooker processand are obviously of circular cross section throughout their length.Subsequently, the circular tubes are placed in a press equipped withsuitable dies so as to flatten the tubes as most clearly shown at 20 inFigs. 2 to 5, leaving circular the ends 2| and 22 and the shortintermediate portions 23 thereof. The spacing of the circular portions2|, 22, and 23 from each other is such that when the tubes I3 areinserted into the fabrication I2, the circular ends 2| and 22 extendinto and slightly through the apertures I8 in the plates I4 and I5,respectively, whereas the intermediate circular portions 23 are in theplanes of the intermediate reinforcing plates I6.

The process or method of forming the several arts and assembling them isa progression of the following steps:

The first step involves the formation of the tubes I3, the forming andpunching of the plates I4, I5, and I6 and the forming of the plates II.Obviously, the formation of these Darts may be carried onsimultaneously, or in seriatim.

The tubes I3, after their formation by the impact extrusion or Hookerprocess, are'placed in a press containing a suitable die whereupon theyare flattened except for the circular end portions 2|, 22, and theintermediate circular portions 23.

The header plates I4 and I5 have the longitudinal and transverse seriesof circular apertures formed therein and the intermediate reinforcingThe third step involves the insertion of the' tubes through theintermediate reinforcing plates I6 with the ends 2| inserted through theapertures I8 in the header plate I4. 'To eifect this insertion, thetubes are obviously inserted through the plates I6 with the fiat partvertically disposed to conform to the shape of the appropriate part ofthe apertures in the plates. When the ends 2| of the tubes I3 have beeninserted through the apertures I8 in the header plate I4, theintermediate circular portions 23 are broughtinto registration with theplates I8. Thereupon the tubes are turned so that they become bonded inthe intermediate plates IS] The amount of turning deends uponcircumstances of structure and objectives. Generally, the turning of thetu es is so as to bring the fiat part parallel to the plane of theconnecting plates I1. Such an arrangement secures the tubes firmly inplace in the reinforcing plates I6 and prevents their vibration ordistortion, or their longitudinal shifting relative to the plates.

In order that the tubes I3, following their initial insertion into theopenings of the partially fabricated plates, may be given the desiredamount of turning, a tool 24 is preferably used. This tool comprises ahandle 25 on which is formed a shank 26 and a pointer 21.

The shank 26 of the tool 24 is of a cross-sectional form to convenientlyfit into the flattened portion of the tubes I3 after being passedthrough the circular end. It is oi. a length which will permit it toextend a considerable distance into the tube thereby providing anextensive area of contact between tool and tube to insure so adequate agrip between the parts as will permit theturning of the tube with littleor no danger of distortion even in cases where the tube may encounterconsiderable frictional resistance in the holes in the respectiveplates.

The pointer 21 and the handle are positioned with respect to the shank26 and each other so that the pointer and the handle 25 are in verticalalinement when the shank 26 is inserted into the tube preparatory toturning the tube. The pointer thus registers with scorings 28 (see Fig.8) concentrically arranged about the circular apertures I8 on the headerplate I4 and thus indicate to the workman the angular position of thelong dimension of the flattened tube.

Once all of the tubes|3 on the assembly are properly positioned, thetube ends 2| are suitably bonded to the header plate I4. This may-bedone by spinning over the ends if they extend at all beyond the face ofthe header plate, or by expandin the tube ends into the header plateapertures, or by some suitable welding or brazing process.

With all of the tubes I3 thus bonded in place, the next step is toinsert all of the tube ends 22 through the apertures I8 in the headerplate I5. Due to their cantilever-like projection beyond the reinforcingplate I6, some of the tubes I3 are likely to sag. 0n the other hand, theinsertion of the tubes or their turning may have warped them a bit fromperfect axial alinement. All of this would combine to make it -ratherdifilcult to insert the many tube ends 22 into the many correspondingapertures I8 of the plate I5, unless some sort of guiding means wereused.

To that end there is provided a mandrel base member 29, on one face ofwhich are mounted a series of mandrels 30 equal in number to theapertures I8 in the header plate I5. These mandrels are rigidly securedto the base member and with the shank 3| equal in diameter to theapertures I8 in the header plate I5. This shank section is slightlylonger than the thickness of the plate I5 and supports an extension 32prac tically equal in "diameter to the interior diameter of the circularend 22 of the tubes I3. The forward end of the extension 32 is taperedat 33 so as to facilitate the entrance of all the mandrels 30 into thetube ends 22 and subsequently bring each tube end into registration withthe shank 3| on its mandrel 30.

Thus, the final step in effecting the assembly is to place the headerplate IS on the mandrels and move the mandrel base into position tobring the tapered ends 33 into engagement with the circular tube ends 22after which the extensions 32 are pushed fully into the tube ends 22 tobring the shoulders 34 into engagement with the tube ends 22: Thereupon,the plate I5 may be shoved inwardly along the shanks 3| over onto thecircular tube ends 22 and the mandrel plate withdrawn.

In effecting this final step of inserting the tube ends 22 into theapertures l8 of the header plate l5, it is obviously necessary to havethe completed assembly of tubes in the fabrication l2 placed on a levelsurface, such as a table or bench, along which the mandrel base may bemoved for initiating registration of the tapered ends 33 with the openends of said tubes.

Due to. the total friction encountered in having a great many mandrelsengaged with a number of tubes, it may be necessary to employ some forceto release the header plate I5 from the mandrels so as to push it ontothe tubes. This could be done by tapping with a light hammer or mallet,or by employing long clamps fitted over the .two ends of theintercooler. On the other hand it might even be accomplished by handscrews which could be made a part of the assembly jig or table, or asuitable power cylinder cular part of said tubes with the non-circularpart of said perforations, seating the circular ends of the tubes in thecircular perforations of one of said header plates, bonding the ends ofsaid tubes to said one header plate, placing the second perforate-headerplate on a base member having mandrels corresponding in number with theperforations in said second header plate, inserting the mandrels intothe other ends of said tubes, shifting said second header plate fromsaid mandrels onto the other ends of said tubes, re-

made without department from the spirit of the invention, the scope ofwhich should be determined by reference to the following claims, thesame being construed as broadly as possible consistent with the state ofthe art.

I claim:

1. The process of constructing a heat exchange unit which comprises,forming a pair of header plates each with circular perforations therein,

forming one or more intermediate reinforcing plates having alongitudinal and transverse series of concentrically intersectingcircular and non circular perforations, forming a plurality of tubes ofnon-circular cross-section intermediate circumoving said mandrel basemember, and bonding said other tube ends to said second header plate.

2. The process of forming a heat exchange unit which comprises,flattening circular tubes throughout their lengths except for shortportions at the ends and at one or more short portions intermediate ofthe ends, forming header plates with a longitudinal and transverseseries -of circular perforations to fit the circular ends of said tubes,forming an intermediate reinforcing plate with a longitudinal andtransverse series of perforations circular on one dimension to fit thecircular portions of said tubes and substantially elliptical on 'theother dimension to accommodate the fiat portion of said tubes,assembling a header plate and a reinforcing plate with the perforationstherein 'alined, inserting said tubes through said alined perforationswith the circular ends of said tubes extending through the perforationsin said one header plate and the intermediate circular parts of saidtubes in registration with the apertures in said intermediatereinforcing plate or plates, turning said tubes to bring the longdimension of the flat portion at an angle to the plane of the longdimension of the elliptical portions of said reinforcing plateperforations, bonding said tube ends to said one header plate, placing asecond perforate header plate on a base member having mandrelscorresponding in number with the perforations in said second headerplate, inserting the mandrels into the other ends of said tubes,shifting said second header plate onto said other ends of said tubes,removing said mandrel base member, and bonding said other tube ends tosaid second header plate.

. HOWARD F. BRINEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

" UNITED STATES PATENTS Ramsaur July 7, 1942

